conditional comment in IE 8

Question

Consider the following, no space before [ and cannot see it as comment in ie 8 F12 console, but the overwrite style cannot be shown.

Don't use compatibility mode in new IEs, it works fine in that way, but not in the real IE 8. What is the problem?

#SectionManagerContent{
        height: 100%;
        width: 100%;
        overflow: auto;
        padding:0px;
        margin:0px;
    }
    </style>
    <!--[if IE 8]>
    <style>
    #SectionManagerContent{
        height: 400px !important;
        overflow:scroll !important;
    }
    </style>
    <![endif]-->